Flexible pipe can be used for fluid transport in various areas, such as conducting production fluids offshore. For example, FIGS. 1A-1B show a flexible pipe 10 similar to that designed by Deepflex, Inc. of Houston, Tex. and disclosed in U.S. Pat. Nos. 6,491,779 and 7,254,933. The pipe 10 can be used in deep sea operations such as disclosed in U.S. Pat. No. 7,073,978. In general, the pipe 10 can have internal diameters of 2, 4, 6, 8, or even up to 16-inches. From inside to outside, the flexible pipe 10 has a number of layers, including a liner layer 11, pressure reinforcement layers 12, hoop reinforcement layers 13, a membrane 14, tensile reinforcement layers 15, and an external jacket 16.
The liner layer 11 is composed of extruded thermoplastic, such as HDPE, PA-11, PVDF and XLPE, and the membrane 14 is made of extruded thermoplastic to seal against compressive loads from external seawater pressure. On the outside, the external jacket 16 is made of extruded thermoplastic to provide external protection to the pipe 10.
Internally, wraps helically wound about the pipe 10 form each of the reinforcement layers 12, 13, and 15. These wraps are made of composite material bonded and stacked together to form composite tapes. As their names imply, the pressure layers 13 are wound for external pressure loads, and the tensile layers 15 are wound for tensile loads. Likewise, the hoop layers 13 are wound for compressive loads.
Because flexible pipes can be used in conditions having high internal and/or external pressures, any rupture in one of the layers such as the pipe's inner layer can allow pressurized fluid to leak through to other surrounding layers. If those surrounding layers have gaps in them such as formed by wrapped tapes, then nothing essentially keeps the pressurized leak from reaching even more layers of the pipe.